Advanced .NET Debugging

John Robbinsjohn@wintellect.com

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About the Presenter – John Robbins• Email: john@wintellect.com / v-jorobb@microsoft.com• Blog: http://www.wintellect.com/wintellog.aspx• Co-founder of Wintellect

– A consulting and education firm dedicated to helping clients ship better software faster

– Concentrate on debugging impossible bugs• Author

– Debugging Microsoft .NET 2.0 Applications, Microsoft Press, 2006– Debugging Microsoft .NET and Microsoft Windows Applications,

Microsoft Press, 2003– Debugging Applications, Microsoft Press, 2000– MSDN Magazine Contributing Editor and Bugslayer Columnist

• Formerly worked at NuMega Technologies-Engineer, Architect, and Product Manager– BoundsChecker (versions 3.0, 4.0 and 5.0)– TrueTime (versions 1.0 and 1.1)– TrueCoverage (version 1.0)– SoftICE (version 3.24)– TrueCoverage for Device Drivers (version 1.0)

Session Code

• Download all the stuff mentioned in class– http://www.wintellect.com/downloads/

DotNetDebuggingCode.zip

Prerequisites

• Build both Debug and Release builds with PDB symbols– Debugging at the assembly level gets old quick (unless

you get paid by the hour!)• Set up a company symbol server to hold your PDB

files– msdn.microsoft.com/msdnmag/issues/02/06/Bugslayer/– Will always keep your symbols lined up

• Set up each machine you touch to at least use the public Microsoft symbol servers– See my Set-VS2010SymbolServer.ps1 script in the

session code

Turn off Just My Code

• The “feature” is to isolate your debugging to only code that is built non-optimized and/or has no debugging symbols

• In real world development, it hides way too much from you

• Disable in Tools, Options dialog, Debugging, General property page

Setting Debugging Properties

• Project Properties Debug property page– You can set

• Command line arguments to pass to the application• The working directory of the application• If you want remote debugging• Native, SQL, and hosting options

What’s that VSHOST thing?

• Makes debugging faster by loading your binary into an already running process

• Allows partial trusted debugging and design time expression evaluation

• Be aware– AppDomain.CurrentDomain.FriendlyName and

Assembly.GetCallingAssembly().FullName will return different values when running under the host process

• Disable in the project properties, Debug page, by unchecking Enable the Visual Studio hosting process

Debugging Partially Trusted

• Now super simple with the Security tab in the project properties

• Enable ClickOnce Security Settings• Select the exact permissions your application

needs• All debugging will be done with those permissions• Any security exceptions will suggest what you

need to fix

Debugging EXE Programs Without Compiling

• To open an EXE to debug by itself– From the File, Open, menu, select Project/Solution– Browse to the EXE directory in the Open Solution dialog– In the Files of Type combo box, select All Project Files– Open the EXE

• You now have a solution with just the EXE– Open source files for the project and set breakpoints just

like normal

Debugging EXE Program without Compiling

• The type of the EXE determines what debugging will be done– If it’s a native EXE, native debugging is the default

• To change– Right click on the EXE and select Properties

• The dialog is actually the native debugging property page

– Change the Debugger Type combo box• Auto = based on EXE type (the default)• Mixed = both managed and native at the same time

The .SUO Problem

• All settings like breakpoints, Watch window values, window layouts, and exception settings, are stored in a hidden file, <Solution Name>.SUO

• Occasionally, this file can become corrupted and lead to serious problems– Problems caused by corrupt .SUO files

• Breakpoints no longer hit• Crashes attempting to display Watch windows• Exception stopping no longer works• Visual Studio crashes when loading a solution

• If Visual Studio is flaking out in any way– Delete the .SUO and that will probably clear up the problem– Get in the habit of saving your breakpoints!

Advanced Breakpoints

• In the debugging dark ages, you had to run your program until it crashed and look at a hex dump listing because there were no breakpoints

• The debugger renaissance age allowed you to set a breakpoint on an address and view a disassembly

• In the debugging modern age, setting a breakpoint on a source line was something magical

• The post-modern age of debugging is all about Advanced Breakpoints

Before Setting Advanced Breakpoints

• Always start debugging first• If you are not debugging, only Intellisense is used

to determine the breakpoint• Once debugging, you have both Intellisense and

symbol tables

Breakpoint Window Codes

Glyph Meaning

Normal breakpoint [enabled and disabled]

Advanced BP (hit count, condition, filter) property set

Mapped BP in ASP/ASP.NET and mapped to an HTML page

Normal tracepoint

Advanced tracepoint (hit count, condition, filter) property set

Mapped TP in ASP/ASP.NET and mapped to an HTML page

Breakpoint or tracepoint error (the BP or TP will never be set)

Breakpoint or tracepoint warning (generally means the source location is not currently in any loaded module)

Location Breakpoints

• Right clicking in the margin or pressing F9 on a line sets what's called a location breakpoint

• The breakpoint does not trigger until that location executes

• .NET does not support data breakpoints like native code

Advanced Location Breakpoints

• Don't forget about Run to Cursor– You can set one-shot breakpoints with it– While debugging, right click on the line and select Run

To Cursor– Default keyboard keystroke: CTRL+F10– If you're not debugging, you'll start debugging and run

to that location

Advanced Location Breakpoints (cont.)

• Select the location up the stack you want to stop on– Press F9 to set a breakpoint– If you right click on the stack item, you can also choose

Run to Cursor

Sub Expression Breakpoints

• You can easily set breakpoints on sub expressions on the same line

• Clicking the margin only sets a breakpoint on the first sub expression on the line

• Select the sub expression you want to stop on and press F9– Only that sub expression will be highlighted as a

breakpoint when debugging• The Breakpoint window shows the character start

of the sub expression

Sub Expression Breakpoints

• When you stop on that sub expression, it will be highlighted yellow

• Clicking in the margin clears the breakpoints in character order

Quickly Breaking on Any Function

• Opening files and scrolling all over the place just to press F9 on a line is a big waste of time

• The debugger is smart enough to hunt down your functions for you

• The magic is all in the Breakpoints dialog– CTRL+B on the default keyboard

Quickly Breaking on Any Function (cont.)

• In the Breakpoint dialog, Function edit control– Type the class name and method/property to break on– The name is dependent on the language

• Use “Module.Function” for VB and C#• Use “Module::Function” for C++/CLI

– The name is case sensitive for C# and C++/CLI– Check Use Intellisense to verify the function name

• If debugging will use Intellisense and the symbols to find the method/property

– Set the Language combo box to the appropriate language

– Leave the column and line set to 1• This sets the breakpoint on the first instruction in

the method/property

Choose Breakpoints Dialog

• The New Breakpoints dialog has even more smarts built into it if a project is loaded

• Instead of typing in the complete class and method, try just the method/property name

• If that method exists in any classes in the solution, the Choose Breakpoints dialog will pop up

Choose Breakpoints Dialog (cont.)

• From the Choose Breakpoints dialog– All methods of that name from all classes are shown– Clicking the All button will set breakpoints on all of them– Clicking the check box next to an item will set or clear it

• If you're debugging a Visual Basic project– You can specify the parameters in the Breakpoints dialog

to skip the Choose Breakpoints dialog• Unfortunately, unlike native C++, typing just the

class name will not pop up the Choose Breakpoints dialog with all the methods and parameters– Use the BreakpointHeler macros

Setting Breakpoints without Source

• Interestingly, you can set breakpoints on Framework API functions– Or any other assemblies you don't have source code for

• The reason why this is cool is that you can get stopped at a known point in the application

• It's also a great way to learn about how things fit together in the .NET Framework

Setting Breakpoints without Source (cont.)

• Steps to setting breakpoints– Bring up the New Breakpoints dialog– Type in the fully qualified name of the method or

property you want to stop on in the Function tab, Function edit control

– Don't worry about case sensitivity– For properties, prefix with "get_" or "set_" as appropriate– Click the Ok button– In Use Intellisense is checked, you'll get a message

about Intellisense not being able to set the breakpoint• Press OK and your breakpoint will be set

Setting Breakpoints without Source (cont.)

• Steps to setting breakpoints (cont.)– Go to the Breakpoints window and verify the breakpoint

has a red circle next to it– If its got a question mark or warning icon in it, the

breakpoint is not set correctly

Setting Breakpoints without Source (cont.)

• In the Breakpoints window you might see something interesting next to the breakpoint– A “+”, indicating a root tree element you can expand– May not always see it, more on this later

• What you're looking at are called "child breakpoints"

Setting Breakpoints without Source (cont.)

• When you run your application, you'll notice you stop in the bowels of the jitted assembly language

• Pull out the Call Stack window and you'll see how you got there

• The number of child breakpoints correspond to the number of overloads for that method

• These breakpoints are set again when you restart debugging

Fun with the Find Combo Box

• If the Breakpoints dialog is too slow for you, use the Find combo box on the toolbar– CTRL+D with the default keyboard

(Edit.GoToFindCombo)– Enter the class and method/property– Press F9– This sets a breakpoint on that function/class

• If you enter just an overloaded method/property breakpoints will be set on all of them

Fun with the Find Combo Box (cont.)• You can open system header and project files from the Find

combo box– Type in the filename and press CTRL+SHIFT+G (Edit.OpenFile)– Press CTRL+SHIFT+G

• You can issue Command window commands from the Find combo box– Enter ">" and the Find Combo turns into a mini Command

window– Neat Command window tricks

• Enter “>open ” or “>of ” (notice space) followed by the first letter of the project file you want to open

• CTRL+/ (Tools.GoToCommandLine) fills in Find Combo Box with last command executed

Location Breakpoint Modifiers

• These are the real power in the debugger– The more you practice these, the faster you'll debug

• The idea is to make the debugger stop only when you want it to stop

• In other words, the debugger only stops when you exactly match your hypothesis

• Supports, hit counts, conditions, and filters

Breakpoint Hit Count

• Skips a breakpoint a specific number of times when running full speed

• Conditions for skipping– Equal to

• Stop only when hit count equals initial value– Multiple of

• Stop every x times (think modulo)– Greater than or equal

• Continues to stop after equaling initial count

Breakpoint Hit Count Steps

• Set a location breakpoint• Right click on the margin red breakpoint dot• From the context menu chose “Hit Count...”• In the Breakpoint Hit Count dialog, combo box,

select the condition• In the edit control that appears, set the number

to skip, etc.• Click OK

Breakpoint Hit Count Steps (cont.)

• The Breakpoints window will show the total execution count

• Use it to see how far you are in loops, etc.• You can also reset the skip count back to zero at

any time by accessing the Breakpoint Hit Count dialog for the breakpoint

Breakpoint Condition

• Probably the modifier you will use the most• Stops when a conditional expression evaluates to

true• Also, can stop when a variable changes• The source language determines the expression

operators– If Visual Basic, “<>” is not equal, etc– If C#, C++/CLI, “!=” is not equal, etc

Breakpoint Condition Steps

• Set a location breakpoint• Right click on the margin red breakpoint dot• From the context menu choose “Condition...”• In the Breakpoints dialog, ensure the Condition

button is checked• Select the "is true" radio button to stop when the

condition is true• In the edit control type the complete expression

to evaluate• Click OK

Breakpoint Condition Steps (cont.)

• If you enter just a variable in the Condition edit control and select the "has changed" radio button– You can break when a variable value changes on that

location• Additionally, you can specify hit counts to stop on

the specific time the condition is true• The Breakpoints window shows the condition for

the breakpoint

Be Careful Setting Breakpoint Conditionals

• Given the following C# code:

• What would happen if you set a conditional BP on the WriteLine with the condition “i = 3”?– Remember: “i == 3” is the correct condition for C#

• My guess would have been the conditional bug discussed two slides ago

• Nope! You get stuck in an infinite loop!• Isn’t that the coolest thing ever!?

int i = 0 ;for ( i = 0 ; i < 10 ; i++ ){ Console.WriteLine ( “i = {0}” , i ) ;}

What Does It Mean?

• The breakpoint condition is evaluated inside the running application– Not inside the debugger context

• What would happen if you try to call a method in the conditional?– The method call executes when evaluating the

breakpoint!• This is tremendous power; use it wisely

– You can really mess up your application• Yes, you can copy a 3GB DB from a breakpoint

– You now can have assertions on the fly!

Assertions On the Fly

• With the ability to call methods, now you can have debug only methods that return true when something’s wrong

• Using that method as a conditional means you’ll only stop when that condition is met

• Essentially, this is like poking in an assertion check before the statement– But there’s no code changing

Assertions On the Fly (cont.)

• Add a method that returns a Boolean– Returns true if there is a problem

• Surround the method with #ifdef DEBUG…#endif– Can’t use [Conditional(“DEBUG”)] as that only works for

void return types• Use the method in any BP condition you want to

stop on if the condition is met#if DEBUG public bool CheckName ( ) { if ( null == m_Name ) { return ( true ) ; } return ( false ) ; }#endif

Filter Breakpoint Modifier

• Easily set per machine, process, and/or thread breakpoints

• Setting a Filter Breakpoint Modifier– Set a location breakpoint– Right click on the breakpoint glyph and select “Filter…”– In the Breakpoint Filter dialog, fill in your condition

• Undocumented syntax– “==“ is supported– The machine/process/thread keywords are case

insensitive

Tracepoints

• Basically breakpoints with a different name– Intended to continue execution

• Custom actions– Print a message (jam in a TRACE statement)

• Put variables in “{}” to evaluate– “\{“ to print a curly brace, “\\” to print a backslash

• Special codes in tracepoint dialog– Execute a VSA macro

The Watch Window (AKA Expression Evaluator)

• The Watch window is one of the finest pieces of software engineering you'll see

• It offers almost infinite flexibility• The most important thing is that in the Watch

window and its cousins (Autos, Locals, Quick Watch, etc) you can click on the value of a variable and change it

• The awesome new data tips are the Watch window in tool tips– All data is fully editable– Pressing the CTRL key makes the Data Tip window see

through– Pin the tips to the source code

Calling Methods in the Watch Window

• It's a great trick for two reasons– It allows you to see data structures that the Watch

window does not display well– You can also have assertions completely on the fly

• Every time you view a property, you're calling the getter method in the Watch window

• Calling a method is as simple as adding the parenthesis and any parameters needed

Calling Methods in the Watch Window (cont.)

• Where does the method/property execute?– In the debuggee

• There are a few rules– Don't do anything more than reading memory– The method must execute in less than 10 seconds

• Interestingly, this same restriction does not apply to methods called by breakpoints

• Does not stop on breakpoints when called from the Watch window– If you want to stop, use the Immediate window

Great Testing Trick

• Drag the expression in a condition down to the Watch window

• This allows you to evaluate and see exactly what variables will trigger the condition you need

• An excellent trick for driving that code coverage as high as possible

• I've changed my coding style to avoid function calls in expressions to make this easier to evaluate

What If the Expression Uses Objects?

• For example:

– How do you change the ae variable since it is an object?– You could change the individual property, but sometimes

you need to change the entire object• The Immediate window to the rescue

– Open the Immediate window• Type in an expression to allocate an object

– Open the Watch window• Add the variable you want to change to the Watch

window• In the Value cell, enter the variable prefixed with a ‘$’

sign– From the above: $x

if ( false == String.IsNullOrEmpty ( ae.Name ) ) ...

SomeClass x = new SomeClass ( ) ;

Data Tips/Watch Window Tricks

• Right click on the data tip to bring up a context menu– Standard options of cut, copy, paste, adding the object to

the watch window and setting hex display• Make Object ID is the very interesting option

– Tells the debugger to watch a particular object in memory no matter where it goes

– Can ID the object with a number• Use 1# in the Watch window for object one, etc.

– Allows you to watch objects even out of scope– If it says “Can’t evaluate” that means the object has been

garbage collected– Can even use the object id in conditional breakpoints

• Allows specific instance breakpoints• C# only feature

What Generation is This Object In?

• Nothing’s stopping you from calling GC.GetGeneration in the Watch window

• Even cooler!– Use Make Object ID to watch an object that’s not in

scope– Pass the Object ID to GC.GetGeneration

• The expression evaluator handles it just fine

Watch Window Format Specifiers

• Like C++, C# lets you format the data display with “,<op>” formatting after the item

Specifiers Format

,d Decimal integer

,h Hexadecimal integer

,nq String not bound by quotes

Watch Window Pseudovariables

• $user– Shows account information for the current thread

• $exception (C# only)– Automatically shown in the Locals window if the

Exception Assistant is disabled

Auto Expanding Your Own Types

• C# only: If your class has an overridden ToString method, the debugger automatically uses it– This alone will let you see much better information with

no extra work on your part• The big magic is in DebuggerDisplayAttribute

– In System.Diagnostic namespace• Now we need an Code Analysis rule that looks for

either– Overridden ToString– DebuggerDisplayAttribute– If neither found, triggers an error

Using DebuggerDisplayAttribute

• Example, a complex number class– Contains the numbers in two private variables, _Real,

and _Imaginary

• Anything inside “{}” is evaluated using the instance of the class

• What’s even cooler?– If a class does not have a DebuggerDisplayAttribute

• The debugger walks the derivation chain looking for the first class that has one set

– If a base class has one, that one is used

[DebuggerDisplay ( "{_Real}.{_Imaginary}i" )]public class ComplexNumber { . . .}

Using DebuggerDisplayAttribute (cont.)• Can be applied to anything other than a method• Can call methods and access properties in the

string– Be careful because syntax evaluation can be different

between languages– The following works in C#, but not Visual Basic

– Visual Basic also does not support calling methods, C# does

[DebuggerDisplay(“Object {count - 2}: {(flag) ? \"yes\" : \"no\"}”)]

Advanced DebuggerDisplayAttribute

• Accepts named parameters– Name – The value to place in the name column– Type – The value to place in the type column

• Example: a KeyPair class that sets the Name named parameter to show the key in the Name column

[DebuggerDisplay ( "{value}" , Name = "{key}" )]class KeyValuePairs

Advanced DebuggerDisplayAttribute (cont.)• Hiding fields and roots can make your Watch

window display much cleaner• Use the DebuggerBrowseableAttribute to set

state– Never – don’t ever display– RootHidden – Don’t display the proxy type, expand the

array items (more on this in a moment)– Collapsed – Don’t expand the class, hide internal

members

Advanced DebuggerDisplayAttribute (cont.)• Example: the complex number class where the

fields are returned by appropriate properties[DebuggerDisplay ( "{_Real}.{_Imaginary}i" )]public class ComplexNumber{ [DebuggerBrowsable ( DebuggerBrowsableState.Never )] private int _Real = 0; public int Real { get { return ( _Real ) ; } set { _Real = value ; } }. . .

Advanced DebuggerDisplayAttribute (cont.)• DebuggerTypeProxyAttribute tells the debugger

to instantiate a different class to display the type– In general, use a private class inside the main type to

handle the display– Will be rare you use this

• See the Using DebuggerDisplayAttribute example in the documentation

Expanding Types with No Source

• Debugger supports expanding types even if you don’t have source– Through AUTOEXP.DLL in Visualizer directories– Magic is Target parameter to DebuggerDisplayAttribute

• See AutoExp project in the session source code

[assembly: DebuggerDisplay ( "Count={Count}" , Target = typeof ( WebCaching.Cache ) )]

Default Visualizers

• Tired of not seeing your strings, HTML, and XML in a normal format in the debugger?

• The default visualizers are here to help– Click on the magnifier in the string type magnifier and

choose how you want to see the data

• A huge productivity boost

Custom Visualizers

• The killer reason for upgrading• Allows you to simply write code to display types

in a more identifiable way• Amazingly simple to write• Amazingly easy to test• Microsoft ships the DataViewManager, DataView,

DataTable, DataSet visualizers, WPF visualizer, and LINQ SQL Queries in the box

Installing Custom Visualizers

• Globally for all users– <VS Dir>\Common7\Packages\Debugger\Visualizers

• For individual users– My Documents\Visual Studio 2010\Visualizers

• Only supports modal dialog visualizers

Writing Visualizers

• After you determine the type you want to display• Create a class library

– Add references to• System.Windows.Forms• Microsoft.VisualStudio.DebuggerVisualizers

– Put those in using directives• Add an assembly level attribute that describes

the type you’re interested in displaying– You can have as many visualizers as you want in a single

assembly

Writing Visualizers (cont.)

• Parameter 1: The visualizer type you are writing• Parameter 2: The serializer to use

– VisualizerObjectSource is the debugger supplied serializer

– Can write custom serializers if you want• Target named param: the type you’re providing a

visualizer for• Desc named param: the display name of your

visualizer[assembly: DebuggerVisualizer ( typeof ( Wintellect.Visualizers.ImageVisualizer ) , typeof ( VisualizerObjectSource ) , Target = typeof ( System.Drawing.Image ) , Description = "Wintellect Image Visualizer" ) ]

Writing Visualizers (cont.)

• Derive your class from DialogDebuggerVisualizer• Implement the trivial Show method

protected override void Show ( IDialogVisualizerService windowService ,

IVisualizerObjectProvider objectProvider ){ // This is all it takes to get the actual object from the // debuggee address space into the debugger. // How simple is that!? Image dbgImage = (Image)objectProvider.GetObject ( );

// Create your dialog here..

// Show it. windowService.ShowDialog ( form );}

Writing Visualizers (cont.)

• Implement a test method you can test the visualizer without the hassle of debugging Visual Studio itself– Create a console app to call the test method

public static void TestImageVisualizer ( object itemToVisualize ){ VisualizerDevelopmentHost visualizerHost = new VisualizerDevelopmentHost ( itemToVisualize , typeof ( ImageVisualizer ) ); visualizerHost.ShowVisualizer ( );}

Cool Free Visualizers

• Regular Expression Visualizers– regex.osherove.com/Articles/RegexKit.html

• Dynamic IL Visualizer– blogs.msdn.com/haibo_luo/archive/

2005/10/25/484861.aspx• ASP.NET Cache Visualizer

– http://blog.bretts.net/?p=11• Mole Visualizer

– www.codeproject.com/KB/macros/MoleForVisualStudioEdit.aspx

– View anything with drill down– Really nice for ASP.NET and WPF

Set Next Statement Command

• A cool hidden trick in the debugger• It allows you to change the instruction pointer to

a different location• A great debugging trick for two reasons

– You can drive your code coverage higher– You can re-execute code to double check conditions

• Be careful, as Set Next Statement can easily crash your program if you put the IP in the wrong place

Using Set Next Statement Command

• Select the yellow instruction arrow and drag it to a different location

• Right click on an executing line when debugging and choose Set Next Statement

Step Over Properties and Operators

• Debugger converts step into a property/operator into a step over– Looks at the code and if it’s small enough, does the step

over• Toggle on and off on the fly while debugging

– Right click in source code and select on context menu

• Always enable Show Threads in Source

– Turns on margin icon that shows you what other threads are executing in the application

Threads Window

Threads Window (cont.)

• Can change the name of a thread in the Name column– Right click on thread and select Rename

• Makes filter breakpoints much easier

• Freeze threads to avoid bouncing around when single stepping– Use the FreezeThawThreads macros to make it easy

• Use InterestingThreads macros to switch all breakpoints to stop only on a specific thread

The .NET Reference Source Code

• Seeing the .NET source is wonderful when debugging

• Setting up your IDE– In Options dialog, Debugging General

• Uncheck “Enable Just My Code (Managed only)”• Check “Enable source server support”

The .NET Reference Source Code (cont.)

• In Options dialog, – In “Symbol file (.pdb) locations” check

• Environment variable: _NT_SYMBOL_PATH• Microsoft Symbol Servers• Add “C:\SYMBOLS\PUBLIC\MicrosoftPublicSymbols*

http://referencesource.microsoft.com/symbols”– In “Cache symbols from symbol servers to this directory”

enter• c:\symbols\Public

• The easy way: use .\Scripts\Set-VS2010SymbolServer.ps1– Part of code disk for this session

The .NET Reference Source Code (cont.)

• Now every time you debug, you’ll download the .NET Reference Source

• Can be very slow the first time you run on a machine• May want to consider only loading symbols

manually– So you pay the download tax only when you need to– Options dialog, Debugging, Symbols

• Uncheck “Search the above locations only when symbols are loaded manually”

– When you want symbols and source• Right click on method in Call Stack window and select

Load Symbols

Problems with .NET Reference Source Downloading

• The debugger can only download a single file at a time

• Would be nice to have the following– A batch download of all supported files into your cache– A way to work with proxy servers– A way to even have .NET source debugging with VS

2005 or CodeGear tools• NetMassDownloader to the rescue

– http://www.codeplex.com/NetMassDownloader– By Kerem Kusmezer and John Robbins– To download all the current sources from Microsoft:

netmassdownloader -d "C:\Program Files\Reference Assemblies\Microsoft\Framework\v4.0" -d C:\windows\Microsoft.NET\Framework\v4.0.30128

Debugging Exceptions

• A little used, but powerful feature of the debugger is the Exceptions dialog

• Checking thrown will stop on the throw statement

Exceptions Handled by the Debugger

• C++ Exceptions– Native code language exceptions

• Common Language Runtime Exceptions– Managed exceptions from .NET applications– Every FCL exception is listed by default

• Managed Debugging Assistants– Diagnostic error notifications from the CLR

• Native Run-Time Checks– The outstanding native /RTC switch exceptions

• Win32 Exceptions– The well known Win32 native exceptions

The Debugging Tricks with Exceptions

• In many cases, you want to stop when the exception is thrown so you can start debugging right from the moment a problem happens

• The steps– Select the exception in the Exception dialog– Check the throw box next to the particular exception

• Great idea to set the entire CLR Exception tree to “Break into the Debugger”– This lets you see how many exceptions are being thrown– Helps you determine performance issues with

exceptions

Adding Your Own Exceptions

• If you want your custom exceptions in the Exception dialog– Click the Add button– Select Common Language Runtime Exceptions in the

Type combo box– Type in the completely qualified name of your custom

exception in the New Common Language Runtime Exceptions dialog

– Data is saved to the .SUO file for the project

Mini Dumps with VS

• Get in the habit of saving dumps when debugging– Debug, Save Dump As command

• Open dumps with File, Open menu– Initiate analysis by clicking on “Debug with Mixed”

• Saves you tons of time!– No longer have to open all dumps with WinDBG+SOS

• Hints– Make sure Symbol Server is set up– For private build binaries and PDB files

• Put them in same directory as .DMP file– Only works for .NET 4.0 applications

IntelliTrace: Why VS 2010 ROCKS!

• Stopping in the debugger is just a “moment in time”– Like looking at a photograph

• A video of everything that happened up to the current point would be even better– That’s exactly what IntelliTrace is all about

• The most exciting advance in debugging in 20 years

• You’ll easily debug problems 25% faster with IntelliTrace

• Caveats– Only in Visual Studio 2010 Ultimate– Today only works with x86 binaries in the debugger

• IntelliTrace integrated into Microsoft Test Manager (MTM) and works with x64

Initially Setting up IntelliTrace

• Key to IntelliTrace– RECORD EVERYTHING!

• IntelliTrace General Page– Enable IntelliTrace events and call information

Initially Setting up IntelliTrace (cont.)

• IntelliTrace, IntelliTrace Events Page– Enable all events– Seriously!

IntelliTrace Usage Hints

• Turn off VSHOST for WPF, Win Forms & console apps– Makes it easier to find your code

• Finding an executed line or method is hidden in the UI– Right click on line– Select “Search for This Line/Method in IntelliTrace”

– Use Information Bar at top of source window to find the exact execution

IntelliTrace Usage Oddness

• So you finish debugging and want to look at the last run log– POOF! The IntelliTrace log disappears as soon as you

stop debugging• Use the Wintellect macro:

IntelliTraceHelper/OpenLastIntelliTraceRecording– Opens the last recorded log– Double click one of the threads to load the log

Remote Debugging

• Remote debugging has gotten even easier with Visual Studio– No longer requires an installation process; now either– XCOPY the required bits– Share the directory with the bits and run– Supports cross CPU debugging

• Bits are in <Install Path>Common7\IDE\Remote Debugger\<CPU>– Where CPU is x86, x64, or ia64

Remote Machine Initial Setup

• On the remote machines run MSVSMON.EXE to get the firewall configured– Must be an administrator on the machine to unblock

ports• Leave the defaults in place• Look at the first line in the MSVSMON.EXE UI and

record the default name of the server

• Optionally, set any permissions using the Options dialog

Local Machine Initial Setup

• Select the Tools, Attach to Process menu• In the Qualifier field, type in the server name of

the remote machine• Click the Refresh button

– When prompted with updating the firewall, select the appropriate level and click OK• You still may not connect as the administrator

account may not have permissions on the other machine

• Start Visual Studio with the same account you logged into the remote machine with– Go through the attach process and you’ll connect

Using MSVSMON.EXE as a Service

• The default usage model requires you to be logged into the remote machine for debugging to work

• Install the Remote Debugging Components from Visual Studio CD/DVD– <Drive>:\Remote Debugger\<cpu>\RDBGSETUP.EXE

• If Visual Studio is installed on the machine– Run <VS DIR>\Common7\IDE\RDBGWIZ.EXE

• For domain-based systems, use LocalService as account

• For workgroups, use an Administrator account for service

• Only accounts in Administrator group can connect and debug

Setting Up a Project

• In the project Property Pages, Debug page– Check Use remote debugging– Specify the remote machine connection string– If the binary is in the same location on both machines

• You do not need to do anything else– If the binary is in a different location on the remote

machine• Select the Start external program radio button• In the edit box, type in the complete drive, path, and

filename to the EXE just like you were typing it on the remote machine

Where Do the PDB Files Go?

• Ideally in a symbol server• For native debugging, symbols are loaded on the

local machine– Where the IDE is running

• For managed debugging, symbols are loaded on the remote machine– Remote debugging includes SYMSRV.DLL so set up the

_NT_SYMBOL_PATH environment variable on the remote machine

• If not using a symbol server– Put the PDB files in the same directories as the binaries

on both machines• Source files are found using paths on the local

machine

Remote Debugging Troubleshooting

• “Access denied” errors in workgroups– Check the security options

• Start Local Security Settings MMC• Go to Local Policies/Security Options• Make sure “Network Access: Sharing and security

model for local accounts” is set to Classic

Questions?

john@wintellect.com